The present invention relates to a compressor of movable vane type and, more particularly, to a movable vane type compressor having at least two tangential sealing portions formed between the inner peripheral surface of a cylinder and the outer peripheral surface of a rotor.
In, for example, Japanese Patent Publication No. 36433/1982 corresponding to German Patent No. P2223087.1, a movable vane type compressor is proposed having a rotor, a casing surrounding the rotor and axial end plates which close both axial ends of the cylinder. A plurality of compression chambers are defined in the space between the outer peripheral surface of the rotor and the inner peripheral surface of the casing by a plurality of tangential sealing portions. The rotor has a plurality of vane grooves each movably receiving a vane which makes a sliding contact with the inner peripheral surface of the casing. As the rotor rotates, the movable vanes move in the vane grooves inwardly and outwardly while sliding along the inner peripheral surface of the casing. Each compression chamber completes one cycle of operation consisting of suction stroke, compression stroke and discharging stroke, as the vanes pass the chamber. A refrigerant is introduced from a refrigeration cycle into the compressor through a substantially bowl-shaped side cover formed on one side surface of the cylinder.
The refrigerant introduced into the side cover is drawn into the compression chambers through suction ports which provide communication between the compression chambers and a refrigerant passage in the side cover in timed relationship to the suction stroke of each compression chamber. In the conventional movable vane type compressor, the refrigerant introduced through a suction port into the refrigerant passage in the side cover is once retarded and then drawn into the compression chambers by the suction force transmitted through the suction ports.
Consequently, a large suction resistance is imposed on the flow of refrigerant flowing into the compression chambers, which, in turn, makes it difficult to improve the volumetric efficiency and the overall adiabatic efficiency.
Accordingly, an object of the invention is to provide a movable vane type compressor which eliminates substantial retardation of the refrigerant introduced into the refrigerant passage through the suction port thereby reducing the suction resistance encountered by the flow of refrigerant flowing into the suction ports.
Another object of the invention is to provide a movable vane type compressor in which the flow velocities of refrigerant directed to all suction ports are equalized to avoid substantial variation of the suction rate according to the difference in position of the work chambers thereby attaining a higher efficiency of the compressor.
Still another object of the invention is to provide a movable vane type compressor in which a drastic change of flowing direction of the refrigerant at the inlet of each suction port is avoided to further decrease the suction resistance.
To this end, according to one aspect of the invention, there is provided a movable vane type in which a refrigerant passage is formed in a hook-like form extending from a suction hole as a starting point to the other end which is substantially closed, and suction ports of compression chambers communicate with the refrigerant passage at a predetermined distance from one another along the length of the passage.
In accordance with another aspect of the invention, there is provided a movable vane type compressor of the kind described, in which the cross-sectional area of a hook-like refrigerant passage is gradually decreased at each juncture of suction ports.
In accordance with still another aspect of the invention, there is provided a movable vane type compressor of the kind described, in which a refrigerant passage is formed in a hook-like form extending in the rotational direction of a rotor.
In accordance with additional advantageous features of the present invention, a portion of the suction passage contacting each suction port has a curved surface curved in conformity with a direction of flow of the refrigerant.
Advantageously, in accordance with the present invention, a portion of each of the suction ports leading from the suction passage to the compression chamber have a wall constituted by a curved surface conforming with a direction of flow of the refrigerant.
Other objects, features and advantages of the invention will become clear from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.